Heat exchanger fins, assemblies and methods

ABSTRACT

A bladed heat exchanger fin, tube assemblies in which the fin is installed, and methods of using the fin. The bladed fin includes a collar and a radial portion extending radially from an axis of the collar. The radial portion has a base region adjacent the collar and first and second sets of blades that radially extend therefrom. Each blade has a span-wise axis that is transverse to the axis of the collar. Each of the first set of blades is revolved about the span-wise axis thereof so as to have radial edges that are axially spaced from each other, and each of the second set of blades is not revolved about the span-wise axis thereof. At least some of the blades of the first set are between at least some of the blades of the second set.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/306,140, filed Feb. 19, 2010, the contents of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The present invention generally relates to heat exchangers, and moreparticularly to fins adapted to be mounted on a heat exchanger tube andconfigured to promote heat transfer to or from the tube.

Heat exchangers are employed within a variety of industries fortransferring heat to or from various types of solids and fluids. As anonlimiting example, the automotive industry employs heat exchangers inair conditioning systems (condensers and evaporators), engine coolingsystems (radiators), and internal climate control systems (heatercores), etc. One type of heat exchanger construction used in theautomotive industry for condensers and evaporators comprises a number ofparallel tubes that are joined to and between a pair of manifolds,creating a parallel flow arrangement. The ends of the tubes aretypically metallurgically joined (brazed, soldered or welded) to tubeports, generally in the form of holes or slots formed in a wall of eachmanifold.

In order to maximize the amount of surface area available fortransferring heat between a fluid (gas and/or liquid) flowing over aheat exchanger tube and a fluid (gas and/or liquid) flowing through thetube, heat exchangers often have a tube-and-fin construction in whichnumerous tubes thermally communicate with high surface area fins. Onetype of fin is in the form of a flat panel having multiple aperturesthrough which multiple parallel tubes are individually inserted. Anothertype of fin is in the form of a sinusoidal center that is positionedbetween adjacent pairs of tubes. In either case, the resultingtube-and-fin assembly is typically oriented so that the edges of thefins face the fluid (e.g., air) flowing between the tubes, i.e., thefins are oriented transverse to the axis of the tubes on which the finsare attached.

Alternative forms of fins that have been suggested include fins thatextend radially from individual heat exchanger tubes. As examples,helical-shaped fins have been proposed that may be integrally formed onthe outer surface of a tube, and disk-shaped fins have been proposedthat are formed separately and then stacked onto the exterior of a tube.Examples of the latter include U.S. Pat. Nos. 4,538,677, 5,337,807,5,617,916, 6,234,245, 7,418,848 and 7,743,821. As evident from thesedocuments, various shapes have been proposed for disk-shaped fins,including corrugated, convoluted and ribbed forms typically defined onfins having an otherwise continuous circular-shaped outer perimeter.Disk-shaped fins have also been proposed having a blade-likeconfiguration, in which individual segments extend radially from thecentral axis of the disk. These segments are generally uniform in sizeand shape, and may lie entirely in the plane of the disk or be deformedto project out of the disk plane, somewhat similar to blades of apropellor or turbine.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a bladed heat exchanger fin, heatexchanger tube assemblies in which the fin is installed, and methods ofusing the fin to transfer thermal energy between fluids.

According to a first aspect of the invention, the bladed heat exchangerfin includes a collar having a tubular-shape so as to define an axis andinner and outer surfaces, and a radial portion extending radially fromthe axis of the collar. The radial portion comprises a base regionadjacent the collar and blades that are attached to and radially extendfrom the base region. The base region defines a base plane that istransverse to the axis of the collar. The blades define an annular arrayof first and second sets of the blades. The annular array defines adiscontinuous perimeter of the bladed heat exchanger fin that isinterrupted by gaps between the first and second sets of blades. Eachblade of the first and second set of blades has a span-wise axis that istransverse to the axis of the collar. Furthermore, each blade of thefirst set of blades is revolved about the span-wise axis thereof so asto have oppositely-disposed radial edges that are axially spaced fromeach other, and each blade of the second set of blades is not revolvedabout the span-wise axis thereof so as to have oppositely-disposedradial edges that are not axially spaced from each other. At least someof the blades of the first set of blades are between at least some ofthe blades of the second set of blades.

According to a second aspect of the invention, the bladed heat exchangerfin is one of a plurality of bladed heat exchanger fins installed on aheat exchanger tube to define a heat exchanger tube assembly. The collarof each of the bladed heat exchanger fins contacts and surrounds anexterior surface of the heat exchanger tube. The heat exchanger tubeassembly may further include one or more bladeless heat exchanger finhaving collars that contact and surround the exterior surface of theheat exchanger tube.

Another aspect of the invention is a method of using a plurality of thebladed heat exchanger fins to transfer thermal energy between twofluids. The method includes installing the bladed heat exchanger fins ona heat exchanger tube so that the collar of each of the bladed heatexchanger fins contacts and surrounds an exterior surface of the heatexchanger tube, flowing a first fluid through an interior passagedefined within the heat exchanger tube, and flowing a second fluidthrough the blades of the bladed heat exchanger fins on the heatexchanger tube. The heat exchanger tube assembly may further include oneor more bladeless heat exchanger fin having collars that contact andsurround the exterior surface of the heat exchanger tube, and aroundwhich the second fluid flows.

A technical effect of the invention is that the bladed heat exchangerfins, alone or in combination with one or more bladeless heat exchangerfins, significantly promote the heat transfer efficiency of a heatexchanger tube in comparison to conventional disk-shaped andhelical-shaped cooling fins. In particular, combinations of blades inwhich some are revolved around their respective pitch axes while othersare not have been shown to enhance heat transfer by promoting thediffusion of heat around a heat exchanger tube without creating adamming effect to fluid flow around the tube. An additional benefit isthat the use of combinations of bladed and bladeless heat exchanger finsis able to promote the structural strength of the fins, particularly ifthe heat exchanger tube is subjected to damage from impingement by soliddebris and high pressure fluids.

Other aspects and advantages of this invention will be betterappreciated from the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1, 2 and 3 are axial, side and perspective views, respectively, ofa disk-shaped bladed fin in accordance with an embodiment of thisinvention.

FIGS. 4 and 5 are axial and side views, respectively, of a disk-shapedbladeless fin adapted for use in combination with the bladed fin ofFIGS. 1 through 3 in accordance with embodiments of this invention.

FIG. 6 is an exploded perspective view of a fixture for assembling thefins of FIGS. 1 through 3 and optionally the fins of FIGS. 4 and 5 on aheat exchanger tube.

FIG. 7 represents a heat exchanger tube on which bladed fins configuredas shown in FIGS. 1 through 3 and bladeless fins configured as shown inFIGS. 4 and 5 have been installed in an alternating pattern to form afin array.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1, 2 and 3 represent what will be referred to herein as a bladedheat exchanger fin 10. This description is attributed to the fin 10having blades 24 and 26 that radiate outward from a central axis 14 ofthe fin 10 to define a perimeter 28 of the fin 10. The fin 10 shown inFIGS. 1 through 3 can also be described as disk-shaped, in that the fin10 has a generally disk-shaped profile such that the perimeter 28 isgenerally circular in shape, though it should be apparent that the fin10 is not required to have circular perimeter 28. The bladed fin 10 isfurther represented in FIGS. 1 through 3 as having a tubular-shapedcollar 12 that defines the axis 14 of the fin 10. The axis 14 will serveas a reference in the following discussion for axial, radial andcircumferential directions of the fin 10. As represented in FIGS. 1through 3, the collar 12 has a cylindrical shape such that it definescylindrical inner and outer surfaces 16 and 18. However, as used hereinthe term “tubular” is not limited to circular cross-sectional shapes,but also encompasses other noncircular cross-sectional shapes, forexample, rectilinear shapes.

The fin 10 has a radial portion 20 that surrounds the collar 12 andextends radially from the axis 14 of the collar 12. The base region 22defines or otherwise lies in a plane that is transverse and (as shown inFIGS. 1 through 3) preferably perpendicular to the axis 14 of the collar12. The radial portion 20 is represented in FIGS. 1 through 3 as alsobeing perpendicular to the axis 14, though it is foreseeable that theradial portion 20 could be transverse to the axis 14 yet disposed atsome angle other than ninety degrees to the axis 14. Furthermore, theradial portion 20 could have a conical shape relative to the axis 14.The radial portion 20 includes a base region 22 that is immediatelyadjacent and surrounds the collar 12, and from which the blades 24 and26 radially extend. The collar 12 and radial portion 20 (which includesthe base region 22 and blades 24 and 26) are represented in FIGS. 1through 3 as being integrally formed to have a one-piece construction,though it is within the scope of the invention that the collar 12 andradial portion 20 could be separately formed and assembled to form thefin 10. Furthermore, it is foreseeable that the blades 24 and 26 couldbe separately formed and then attached to the base region 22.

The blades 24 and 26 are arranged on the fin 10 to define an annulararray of blades. For purposes of the following discussion, the blades 24and 26 can be said to define two separate sets of blades, though it isalso within the scope of the invention to make use of additional sets ofblades. In FIG. 1, the blades 24 and 26 are arranged in an alternatingpattern, with each blade 24 being circumferentially disposed between apair of the blades 26, and vice-versa. The blades 24 and 26 are spacedapart from each other by a radial gap 30, with the result that eachblade 24 and 26 defines an oppositely-disposed pair of radial edges 36and 38, respectively. As a result of the gaps 36, the perimeter 28 ofthe bladed fin 10 is discontinuous as a result of being interrupted bythe gaps 30 between adjacent pairs of blades 24 and 26.

Each blade 24 and 26 can be described as having a span-wise axis 32. Asused herein, the span-wise axis 32 of each blade 24 and 26 is preferablyequi-distant from the radial edges 36 and 38 of the blade 24 and 26,respectively. Each span-wise axis 32 coincides with a radial 34 of theradial portion 20 of the fin 10. In the embodiment of FIGS. 1 through 3,the span-wise axis 32 of each blade 24 and 26 also lies within the planedefined by the base region 22, and as such is perpendicular to the axis14 of the collar 12. However, the span-wise axes 32 of the blades 24 and26 are not required to be perpendicular to the axis 14, and as suchcould be inclined relative to the axis 14, for example, as a result ofthe radial portion 20 having a conical shape or otherwise being at anangle other than perpendicular to the axis 14.

The blades 24 and 26 differ from each other in that each blade 24 isrevolved about its span-wise axis 32, somewhat similar to the blades ofa propellor or turbine, whereas the blades 26 are not. Instead, eachblade 26 lies entirely within the plane defined by the base region 22.The junction between the base region 22 and each blade 24 is representedin FIG. 1 as defining a linear crease 40 that is transverse but notperpendicular to a radial 34 of the radial portion 20. In theconfiguration shown in FIGS. 1 through 3, the span-wise axis 32 of eachblade 24 still lies within the plane defined by the base region 22, butthe radial edges 36 of each blade 24 are axially spaced from each other.As evident from FIG. 2, because the span-wise axes 32 of the blades 24lie in the plane defined by the base region 22, the radial edges 36 ofthe blades 24 are located on opposite sides of the base plane.

Bladed fins 10 of the type shown in FIGS. 1 through 3 are preferablyused in combination with multiple other fins, at least some of whichhaving the same configuration as shown in FIGS. 1 through 3. Asrepresented in FIG. 6, these fins 10 can then be installed on a heatexchanger tube 72 to define a heat exchanger tube assembly 70. Thecollar 12 of each bladed fin 10 contacts and surrounds an exteriorsurface 74 of the tube 72, and the axis 14 of each collar 12 preferablycoincides with the axis 80 of the tube 72.

As represented in FIG. 6, the tube assembly 70 further includes aplurality of bladeless heat exchanger fins 50 of a type represented inFIGS. 4 and 5, such that the fins 10 and 50 define a linear array offins 10 and 50 on the tube 72. The term “bladeless” is intended to helpdifferentiate the fins 50 of FIGS. 4 and 5 from the fins 10 of FIGS. 1through 3, in that the bladeless fins 50 lack any discrete radialelements separated by radial gaps, in contrast to the radial blades 24and 26 of the fins 10 that are separated by the radial gaps 30. Asevident from FIGS. 4 and 5, each bladeless fin 50 has a collar 52 thatdefines an axis 54 of the fin 50, and a radial portion 60 that extendsradially from the axis 54 of the collar 12 to define a continuousperimeter 62 (i.e., uninterrupted by gaps). As with the fin 10 of FIGS.1 through 3, the radial portion 60 of the bladeless fin 50 isrepresented as being perpendicular to the axis 54, though the radialportion 60 could be disposed at some other transverse angle to the axis54, as well as have a conical shape. As evident from FIG. 6, the collar52 of each bladeless fin 50 contacts and surrounds the exterior surface74 of the tube 72, so that its axis 54 coincides with the axis 80 of thetube 72.

As also evident from FIG. 6, the bladeless fins 50 are disposed betweenpairs of the bladed fins 10. Though the thermal performance of the tubeassembly 70 tends to be reduced somewhat by the presence of thebladeless fins 50, the configuration represented in FIG. 6 promotes thedurability of the fins 10 and, therefore, the overall durability of thetube assembly 70. In particular, the bladeless fins 50 help to supporttheir adjacent bladed fins 10 in the event that the tube assembly 70 issubjected to impacts, for example, from solid debris or high-pressurefluids, as can occur with heat exchangers used in automotiveapplications.

FIG. 6 further represents the tube assembly 70 as being assembled with amanifold 82, as a result of one end of the tube 72 being inserted in aport 84 defined in the manifold 82. Those skilled in the art willappreciate that the opposite end of the tube 72 would also be similarlyreceived in a port of a second manifold. In use, a fluid (gas or liquid)flowing within the manifold 82 would flow through a passage 78 definedby the interior wall 76 of the tube 72. Heat transfer to or from thefluid within the tube 72 occurs as a result of flowing a second fluid(gas or liquid) around the exterior of the tube 72 and, therefore,through the fins 10 and 50 and, in particular, through the blades 24 and26 of the bladed fins 10. Due to the presence of the blades 24 and 26,and in particular the different orientations of the blades 24 and 26,greater turbulation is achieved within the flow of the second fluid,which in turn promotes heat transfer between second fluid and the fins10 and 50.

The angle at which the blades 24 are revolved around their respectiveaxes 32 affects the heat transfer efficiency as well as the pressuredrop of flow through the fins 10 and 50. A maximal revolution angle willincrease turbulation and therefore promote heat transfer, but will alsoincrease the pressure drop of flow through the fins 10 and 50. On theother hand, a minimal angle will decrease the pressure drop through thefins 10 and 50, but also decrease turbulation and therefore reduce theheat transfer of the tube assembly 70. In FIG. 2, the revolution angleof the blades 24 is about 60 degrees to the axis 32. Generally, asuitable range for the revolution angle is about 30 to less than 90degrees, with a preferred range being about 45 to about 75 degrees.

The fins 10 and 50 and the tube 72 can be formed from a variety ofmaterials, notable but nonlimiting examples of which include aluminumalloys widely used in heat exchanger applications. Those skilled in theart will appreciate that, depending on the size and geometry of the fins10 and 50 and tube 70 and the type of material used to form the fins 10and 50 and tube 72, the fins 10 and 50 can be secured to the tube 72with an interference fit and/or by a bonding method, includingmetallurgical bonding techniques such as brazing, soldering and welding.FIG. 7 represents one such assembly method as employing a fixtureassembly 100 comprising a fin housing subassembly 102 formed by twocomplementary fin housing members 104 and 106, a tube housingsubassembly 108 formed by two complementary tube housing members 110 and112, and a fin installation subassembly 114 formed by two complementaryfin installation members 116 and 118. The fin housing members 104 and106 have complementary channels 120 that together define a cavity sizedto accommodate an array of fins 10 and 50. Similarly, the tube housingmembers 110 and 112 have complementary channels 122 that together definea cavity sized to accommodate one end of the tube 72, and the fininstallation members 116 and 118 have complementary channels 124 thattogether define a cavity sized to accommodate the opposite end of thetube 72. Finally, the fin installation members 116 and 118 further havecomplementary semi-cylindrical members 126 that together define aplunger sized to be received in the cavity defined by the fin housingmembers 104 and 106 for the purpose of forcing the fins 10 and 50 ontothe tube 72, such that the fins 10 and 50 can be retained on the tube 72by an interference fit. Other fixtures and methods for assembling thefins 10 and 50 on the tube 72 could also be employed.

Those skilled in the art will also appreciate that an optimalcross-section, size and length of the tube 72, an optimal cross-section,size and length of each blade 24 and 26, and an optimal number anddistribution of the fins 10 and 50 on the tube 72 will depend on theparticular application for which the tube assembly 70 is intended. Inaddition to air-conditioning applications such as condensers andevaporators, other applications for the present invention include, butare not limited to, engine cooling systems (radiators), internal climatecontrol systems (heater cores), oil coolers, and exhaust gas heatexchangers.

While the invention has been described in terms of specific embodiments,it is apparent that other forms could be adopted by one skilled in theart. Therefore, the scope of the invention is to be limited only by thefollowing claims.

1. A bladed heat exchanger fin comprising: a collar having atubular-shape so as to define an axis and inner and outer surfaces; aradial portion extending radially from the axis of the collar, theradial portion comprising a base region adjacent the collar and bladesthat are attached to and radially extend from the base region, the baseregion defining a base plane that is transverse to the axis of thecollar, the blades defining an annular array comprising first and secondsets of the blades that define a discontinuous perimeter of the bladedheat exchanger fin that is interrupted by gaps between the first andsecond sets of blades, each blade of the first and second set of bladeshaving a span-wise axis that is transverse to the axis of the collar;each blade of the first set of blades being revolved about the span-wiseaxis thereof so as to have oppositely-disposed radial edges that areaxially spaced from each other; each blade of the second set of bladesnot being revolved about the span-wise axis thereof so as to haveoppositely-disposed radial edges that are not axially spaced from eachother; and at least some of the blades of the first set of blades beingbetween at least some of the blades of the second set of blades.
 2. Thebladed heat exchanger fin according to claim 1, wherein the base planeis perpendicular to the axis of the collar.
 3. The bladed heat exchangerfin according to claim 1, wherein the span-wise axis of each blade ofthe first and second sets of blades is perpendicular to the axis of thecollar and coincides with a radial of the radial portion.
 4. The bladedheat exchanger fin according to claim 1, wherein the radial edges of thefirst set of blades are located on opposite sides of the base plane. 5.The bladed heat exchanger fin according to claim 1, wherein the radialedges of the second set of blades are located within the base plane. 6.The bladed heat exchanger fin according to claim 1, wherein thespan-wise axis of each blade of the first set of blades lies within thebase plane.
 7. The bladed heat exchanger fin according to claim 1,wherein each blade of the second set of blades lies entirely within thebase plane.
 8. The bladed heat exchanger fin according to claim 1,wherein each blade of the first set of blades adjoins the base region todefine a linear crease that is transverse but not perpendicular to aradial of the radial portion.
 9. The bladed heat exchanger fin accordingto claim 1, wherein each blade of the first set of blades is between apair of the blades of the second set of blades.
 10. The bladed heatexchanger fin according to claim 1, wherein the bladed heat exchangerfin is one of a plurality of bladed heat exchanger fins according toclaim 1 that are installed on a heat exchanger tube to define a heatexchanger tube assembly, the collar of each of the bladed heat exchangerfins contacts and surrounds an exterior surface of the heat exchangertube.
 11. The heat exchanger tube assembly according to claim 10,wherein the heat exchanger tube assembly further comprises a bladelessheat exchanger fin comprising a collar that contacts and surrounds theexterior surface of the heat exchanger tube, an axis that coincides withthe axis of the heat exchanger tube, and a radial portion that extendsradially from the collar to define a continuous perimeter of thebladeless heat exchanger fin, the bladeless heat exchanger fin beingdisposed between a pair of the bladed heat exchanger fins.
 12. The heatexchanger tube assembly according to claim 10, wherein the heatexchanger tube is assembled with a pair of manifolds and opposite endsof the heat exchanger tube are received in ports in the manifolds.
 13. Amethod of using a plurality of bladed heat exchanger fins each accordingto claim 1, the method comprising: installing the bladed heat exchangerfins on a heat exchanger tube so that the collar of each of the bladedheat exchanger fins contacts and surrounds an exterior surface of theheat exchanger tube; flowing a first fluid through an interior passagedefined within the heat exchanger tube; and flowing a second fluidthrough the blades of the bladed heat exchanger fins on the heatexchanger tube.
 14. The method according to claim 13, the method furthercomprising installing a plurality of bladeless heat exchanger fins onthe heat exchanger tube, each of the bladeless heat exchanger finscomprising a collar that contacts and surrounds the exterior surface ofthe heat exchanger tube, an axis that coincides with the axis of theheat exchanger tube, and a radial portion that extends radially from thecollar to define a continuous perimeter of the bladeless heat exchangerfin, at least some of the bladeless heat exchanger fins being disposedbetween pairs of the bladed heat exchanger fins.
 15. A bladed heatexchanger fin comprising: a collar having a tubular-shape so as todefine an axis and inner and outer surfaces; a radial portion extendingradially from the axis of the collar, the radial portion comprising abase region adjacent the collar and blades that are attached to andradially extend from the base region, the base region defining a baseplane that is perpendicular to the axis of the collar, the bladesdefining an annular array comprising first and second sets of the bladesthat define a discontinuous perimeter of the bladed heat exchanger finthat is interrupted by gaps between the first and second sets of blades,each blade of the first and second sets of blades having a span-wiseaxis that is perpendicular to the axis of the collar and coincides witha radial of the radial portion; each blade of the first set of bladesbeing revolved about the span-wise axis thereof so that the span-wiseaxis of each blade of the first set of blades lies within the base planeand each blade of the first set of blades has oppositely-disposed radialedges that are axially spaced from each other and located on oppositesides of the base plane; each blade of the second set of blades notbeing revolved about the span-wise axis thereof and each blade of thesecond set of blades lying entirely within the base plane; and eachblade of the first set of blades being between a pair of the blades ofthe second set of blades.
 16. The bladed heat exchanger fin according toclaim 15, wherein each blade of the first set of blades adjoins the baseregion to define a linear crease that is transverse but notperpendicular to a radial of the radial portion.
 17. The bladed heatexchanger fin according to claim 15, wherein the bladed heat exchangerfin is one of a plurality of bladed heat exchanger fins according toclaim 15 that are installed on a heat exchanger tube to define a heatexchanger tube assembly, the collar of each of the bladed heat exchangerfins contacts and surrounds an exterior surface of the heat exchangertube, and the axis of each of the collars coincides with an axis of theheat exchanger tube.
 18. The heat exchanger tube assembly according toclaim 17, wherein the heat exchanger tube assembly further comprises aplurality of bladeless heat exchanger fins, each of the bladeless heatexchanger fins comprising a collar that contacts and surrounds theexterior surface of the heat exchanger tube, an axis that coincides withthe axis of the heat exchanger tube, and a radial portion that extendsradially from the collar to define a continuous perimeter of thebladeless heat exchanger fin, at least some of the bladeless heatexchanger fins being disposed between pairs of the bladed heat exchangerfins.
 19. The heat exchanger tube assembly according to claim 18,wherein the heat exchanger tube is assembled with a pair of manifoldsand opposite ends of the heat exchanger tube are received in ports inthe manifolds.
 20. A method of using a plurality of bladed heatexchanger fins each according to claim 15, the method comprising:installing the bladed heat exchanger fins on a heat exchanger tube sothat the collar of each of the bladed heat exchanger fins contacts andsurrounds an exterior surface of the heat exchanger tube and the axes ofthe collars coincide with an axis of the heat exchanger tube; flowing afirst fluid through an interior passage defined within the heatexchanger tube; and flowing a second fluid through the blades of thebladed heat exchanger fins on the heat exchanger tube.
 21. The methodaccording to claim 20, the method further comprising installing aplurality of bladeless heat exchanger fins on the heat exchanger tube,each of the bladeless heat exchanger fins comprising a collar thatcontacts and surrounds the exterior surface of the heat exchanger tube,an axis that coincides with the axis of the heat exchanger tube, and aradial portion that extends radially from the collar to define acontinuous perimeter of the bladeless heat exchanger fin, at least someof the bladeless heat exchanger fins being disposed between pairs of thebladed heat exchanger fins.